At launch, the service was free to organisations with fewer than 20 users (IIRC). In the halcyon days of 2007, when Google launched the $US50/user/year Premium edition, it said the following about the suite back in February 2007:

“Google Apps also won't forget its roots anytime soon. The Standard and Education Editions will continue to be offered for free, and we'll keep working on all three flavors of Google Apps with the help of feedback from all of you.”

From that quote we can deduce that "anytime soon", for Google, lasts five years and ten months.

The Chocolate Factory has offered up the following paragraph to explain its decision:

“When we launched the premium business version we kept our free, basic version as well. Both businesses and individuals signed up for this version, but time has shown that in practice, the experience isn't quite right for either group. Businesses quickly outgrow the basic version and want things like 24/7 customer support and larger inboxes. Similarly, consumers often have to wait to get new features while we make them business-ready.”

Google’s solution is to make all new business customers for Apps pay. Existing customers will still enjoy free access to the suite and individuals can still sign up for free accounts.